Lumpy Cold Idle. Please help...

My 2002 Jimny 1.3 has only done 27,000 miles and things are now going wrong
On idle (when cold), the revs fluctuate between 1500rpm to just under 1000rpm, occasionally dropping to about 600rpm. When the revs get low it sounds like it is on the verge of dying if you don't give it some gas.
I gave it a motorway blast to try and solve it but the morning after there was no joy
After a bit of research I decided to change the PCV valve, but this has not done anything...
Thought this to be very odd as it only does it when cold...

This used to be my mums car so it's been in our family it's entire life and this is our very first mechanical problem in nearly 10 years!!!
Any help would be much appreciated

(p.s. i'm a first time poster)

Hi 0202jimny, welcome to the forum and world of Jimny

Don't worry about it, it's probably just missing it's mum and will eventually settle down :silly:

when did it last have a service or any work done on it ?
does this only happen when it's cold or was it still doing it after the motorway blast - or was it only after starting when it had got cold again?

Hi Halford,
I hope it isn't missing it's mum as i definately keep it cleaner than she did! :lol:
It was last serviced in October and had spark plugs changed, oil change etc. at our local kwik fit.
As soon as it gets up to temperature it runs perfectly, and it doesnt happen when it's started up whilst warm.
:S
Charlie

on 02 plate with only 27k on the clock... That car has been sat around for along time!

Maybe mucky injectors? Get some injector cleaner and give it a good run! Costs all of a few quid... might be worth a tank of premium fuel too!

Air inlet temp sensor on the airbox?

Hi mate, Welcome to Big jimny.

Take the car to your local Suzuki dealer and get them to plug it into there computer that will tell you straight away where the issue is. The only other thing i can think of is maybe a sticky/stuck EGR valve, that would cause the strange idle and missing.

Are there any dash light's coming on? Or is it throwing any error codes?

Andrew

I had this recently on a jimny i bought, was rough for the first 30 seconds or so, turned out to be the previous owner hadn't tightened up the spark plugs properly, im thinking the expansion when it warmed up was enough to make them seal, i changed the plugs and tightened them in properly and the problem went away completely. this was on a g13bb.

What you need to do is clean the EGR valve out, remove the throttle body and give in a good clean out including taking the idle air control valve out and cleaning and freeing that off too. Sounds like the EGR, IAC, or throttle postion sensor is giving the the ECU a false reading. Doing what I have suggested I'm sure will cure your problem. ( all easy enough to do yourself mate)


Steve.

Do you feel competent enough to tackle it mate ?


Steve.

Thanks everyone, some great responses...

The car was used everyday for the school run, however the poor thing has never seen a spec of mud in its life....only some occasional snow.
Picked up some Wynn's injector cleaner today, so will put that through and see what happens...

Steve - that all sounds a bit daunting, but I'm sure ill be able to give it ago...

Charlie.

Don't worry mate it's only a few bolts and a few pipes really. Give us a shout if you get stuck fella and will be glad to help.


Steve.

I bet it's that bloody coolant temperature sensor that's causing all the problems :dry:

Municipal Waste wrote: I bet it's that bloody coolant temperature sensor that's causing all the problems :dry:

I will bet your right aswell. Mine was doing this and that was the problem. The temp sensor tells the ecu it is at running temp and the ecu adjusts the IAC. If the sensor goes tits up the IAC will fluctuate. First case is disconnect the IAC plug and if it settles at around 1400rpm you can more or less guarantee it's the temp sensor.